Heat exchanger having means for reducing thermal stress

ABSTRACT

The present invention relates to a heat exchanger having a means for reducing thermal stress. An object of the present invention is to provide an integrated heat exchanger configured to cool two types of heat exchange media having different temperatures, the heat exchanger having a means for reducing thermal stress and having a flow distribution structure in a tank in order to effectively disperse thermal stress caused by a temperature difference.

TECHNICAL FIELD

The present invention relates to a heat exchanger, and more particularly, to an integrated heat exchanger configured to cool two types of heat exchange media having different temperatures, i.e., a heat exchanger having a means for reducing thermal stress, which is capable of effectively dispersing thermal stress caused by a temperature difference.

BACKGROUND ART

In general, not only components such as an engine for operating a vehicle are provided in an engine room of the vehicle, but also various heat exchangers such as a radiator, an intercooler, an evaporator, and a condenser for cooling the components such as the engine in the vehicle or adjusting an air temperature in an interior of the vehicle are provided in the engine room of the vehicle. In general, heat exchange media flow in the heat exchangers. The heat exchange medium in the heat exchanger exchanges heat with outside air present outside the heat exchanger, such that the cooling operation or the heat dissipation is performed.

In most cases, a single type of heat exchange medium flows in the heat exchanger. However, as necessary, heat exchangers, in which two types of heat exchange media flow, are sometimes integrated. For example, in the case of a radiator and an oil cooler of the vehicle, a coolant for cooling the engine flows in the radiator, and oil such as engine oil or transmission oil flows in the oil cooler. Of course, the radiator and the oil cooler are sometimes configured as separate devices. However, to improve spatial utilization of the engine room, the radiator and the oil cooler are often integrated as a structure such as a water-cooled oil cooler structure configured to cool oil by using a coolant.

A portion of the heat exchanger where the heat exchange is mainly performed is a portion where tubes are stacked, and this portion is generally called a core of the heat exchanger. In the related art, the integrated heat exchanger, in which two types of heat exchange media flow, often has a structure in which cores in which the heat exchange media flow are connected in series. Meanwhile, recently, a structure in which the cores are connected in parallel has been sometimes adopted. FIG. 1 illustrates an example of an integrated heat exchanger in the related art that has a structure in which cores in which two types of heat exchange media flow are connected in parallel. In the case of the integrated heat exchanger according to the example illustrated in FIG. 1 , the structure in which the two cores are connected to each other in parallel is similar to a structure of a heat exchanger in which a single type of heat exchange medium flows. In more detail, the heat exchangers are arranged in two rows, and a partition means is provided in a header tank to isolate the heat exchange media. A configuration of a two-row heat exchanger is disclosed well in Korean Patent No. 0825709 (“HEAT EXCHANGER”, Apr. 22, 2008).

Specifically, a heat exchanger 100 includes: a pair of header tanks 100 spaced apart from each other at a predetermined distance and provided side by side; and a plurality of tubes 200 each having two opposite ends fixed to the header tanks 100 and configured to define flow paths for a refrigerant, and additionally includes a plurality of fins interposed between the tubes 200. In this case, the tubes 200 are provided in two rows in a forward/rearward direction. The header tanks 100 each include a partition wall 125 extending in a longitudinal direction in the header tank to partition a space that communicates with the respective tubes. Therefore, first and second heat exchange media, which respectively flow in the tubes 200 disposed in first and second rows, may be isolated and flow without meeting together. Of course, an inlet port and a discharge port, which are paired, are separately provided for each of the heat exchange media in the header tank 100. FIG. 1 illustrates that first and second inlet ports and first and second discharge ports are provided in the header tanks in opposite directions in the form of a cross-flow in which the heat exchange media flow in one direction. However, in the case of a U-flow in which the heat exchange media flow in a U shape, the first and second inlet ports and the first and second discharge ports may be provided in the same direction in the header tanks.

In the integrated heat exchanger provided as described above, two types of heat exchange media, which are different in properties like a coolant and oil, may flow, or two types of heat exchange media, which are different in temperature ranges like a low-temperature coolant and a high-temperature coolant, may flow, such that the integrated heat exchanger is operated in various ways. In any case, because the heat exchange media are very different in temperature ranges in case that the two types of heat exchange media flow, a significant temperature difference is defined between the front and rear cores. When a temperature distribution is unbalanced as described above, a degree of thermal deformation varies depending on positions. For this reason, there is a problem in that thermal stress is concentrated at a particular site of the heat exchanger. In the case of the above-mentioned integrated heat exchanger, the thermal stress concentration is highest at a portion where the front and rear cores are separated. Because the thermal stress concentration caused by thermal deformation is a major factor that causes damage to or breakage of the heat exchanger, there is a need for design for coping with the thermal stress concentration.

DOCUMENT OF RELATED ART Patent Document

-   1. Korean Patent No. 0825709 (“HEAT EXCHANGER”, Apr. 22, 2008)

DISCLOSURE Technical Problem

Therefore, the present invention has been made in an effort to solve the above-mentioned problems in the related art, and an object of the present invention is to provide an integrated heat exchanger configured to cool two types of heat exchange media having different temperatures, i.e., a heat exchanger having a means for reducing thermal stress, which is capable of effectively dispersing thermal stress caused by a temperature difference.

Technical Solution

To achieve the above-mentioned object, a heat exchanger 1000 according to the present invention includes: a pair of header tanks 100 each having therein a fluid flow space defined by coupling a header 110 and a tank 120, the pair of header tanks being spaced apart from each other at a predetermined distance and provided side by side; and a plurality of tubes 200 each having two opposite ends fixed to the header tank 100 and configured to define flow paths for heat exchange media, the plurality of tubes being arranged in two rows in a forward/rearward direction, in which an internal space of the header tank 100 is isolated and divided by a partition wall 125 into front and rear heat exchange parts, in which the heat exchange media having different average temperatures flow in the front and rear heat exchange parts, respectively, and in which the partition wall 125 has a thermal stress reducing means.

As one embodiment of the thermal stress reducing means, the thermal stress reducing means may be a flow distribution structure formed on the tank 120 in a partition wall vicinity region adjacent to the partition wall 125 that is a boundary line between the front and rear heat exchange parts, and the flow distribution structure may be formed so that a flow rate of the heat exchange medium flowing in the internal space of the tube 200 in the partition wall vicinity region is relatively lower than a flow rate of the heat exchange medium flowing in the internal space of the tube 200 in the remaining region.

In this case, the flow distribution structure may be a flow rate adjustment baffle 121 having one end fixed to an inner surface of the tank 120, and the other end disposed to be spaced apart from the internal space of the tube 200, the flow rate adjustment baffle being formed to reduce a flow rate of the heat exchange medium flowing in the internal space of the tube 200 in the partition wall vicinity region.

Alternatively, the flow distribution structure may be a flow rate adjustment rib 122 formed as a part of the tank 120 protrudes to an inside of the header tank 100 and an end of a protruding portion is disposed to be spaced apart from the internal space of the tube 200, and the flow rate adjustment rib may be formed to reduce a flow rate of the heat exchange medium flowing in the internal space of the tube 200 in the partition wall vicinity region.

In addition, the flow distribution structure may be formed in one of the front and rear heat exchange parts where a temperature of the heat exchange medium is relatively high. More specifically, in the heat exchanger 1000, a temperature of the heat exchange medium flowing in the rear heat exchange part may be higher than a temperature of the heat exchange medium flowing in the front heat exchange part, and the heat exchanger the flow distribution structure may be formed in the rear heat exchange part.

In addition, the flow distribution structure may be applied to all positions of the tubes 200.

In addition, the flow distribution structure may be formed to be spaced apart from only a position opposite to a position of the tube 200.

The flow distribution structure may be formed to correspond to a range of 10 to 20% of a width of the tube 200.

As another embodiment of the thermal stress reducing means, the thermal stress reducing means may be an air pocket 123 formed in the form of an empty space in the partition wall 125.

In this case, the air pocket 123 may extend in an extension direction of the partition wall 125.

In addition, the air pocket 123 may be formed to be opened at an end directed toward the header 120.

In this case, an opened portion of the air pocket 123 may be sealed by a gasket 150 provided at a portion where the header 110 and the tank 120 are coupled.

In addition, in this case, the gasket 150 may have a sealing protrusion 151 protruding at a position corresponding to the opened portion of the air pocket 123.

In addition, the heat exchanger 1000 may have a leak check path 124 formed in the tank 120 and provided in the form of a flow path that allows the air pocket 123 to communicate with the outside.

In addition, the heat exchanger 1000 may be a radiator in which a high-temperature coolant and a low-temperature coolant flow.

Advantageous Effects

According to the present invention, in the integrated heat exchanger configured to cool two types of heat exchange media having different temperatures, the flow distribution structure is provided in the tank, or the air pocket is formed in the partition wall in the tank, which makes it possible to effectively disperse thermal stress caused by a temperature difference. More specifically, in the heat exchanger of the present invention, the cores of the heat exchanger include the front and rear cores to cool the two types of heat exchange media, and it is known that thermal stress concentration is highest at the boundary portion between the front and rear cores. In this case, in the present invention, as one embodiment, the thermal stress concentration is mitigated by adopting the structure in which the flow rate is decreased by partially blocking the end of the tube at the boundary portion where the tubes are disposed adjacent to one another. In particular, in the present invention, the flow distribution is implemented by the baffle or the tank inward protruding structure formed adjacent to the partition wall formed in the tank. Alternatively, as another embodiment, the air pocket is formed in the partition wall, such that thermal insulation is effectively implemented between the front and rear sides.

Because the flow distribution structure is provided as described above, a temperature gradient at the boundary portion is more gently defined during the process in which the heat exchange media having different temperature ranges flow in the front and rear cores, which makes it possible to solve the problem of the temperature imbalance. Of course, the thermal stress may be effectively dispersed, thereby ultimately preventing the problem of damage to and breakage of connection between the header and the tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating an example of an integrated heat exchanger in the related art.

FIG. 2 is a perspective view of a first embodiment of an integrated heat exchanger tank structure of the present invention.

FIG. 3 is a cross-sectional view of the first embodiment of the integrated heat exchanger tank structure of the present invention.

FIG. 4 is a perspective view of a second embodiment of the integrated heat exchanger tank structure of the present invention.

FIG. 5 is a cross-sectional view of the second embodiment of the integrated heat exchanger tank structure of the present invention.

FIG. 6 is a view of examples of temperature gradients in the related art and the present invention.

FIG. 7 is a graph for comparing temperature gradients between the related art and the present invention.

FIG. 8 is a view illustrating deformation of a baffle caused when a temperature difference between heat exchange media at two sides of the integrated heat exchanger is large.

FIG. 9 is a cross-sectional view of a third embodiment of the integrated heat exchanger tank structure of the present invention.

FIG. 10 is a cross-sectional view of a fourth embodiment of the integrated heat exchanger tank structure of the present invention.

MODE FOR INVENTION

Hereinafter, a heat exchanger according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

The heat exchanger described in the present invention is an integrated heat exchanger configured such that different types of heat exchange media having different temperatures independently flow, particularly a heat exchanger in which tubes are arranged in two front and rear rows, and cores, i.e., heat exchange parts, where the heat exchange is mainly performed, are doubly provided at front and rear sides. Specifically, as described briefly with reference to FIG. 1 , a heat exchanger 1000 may include: a pair of header tanks 100 each having therein a fluid flow space defined by coupling a header 110 and a tank 120, the pair of header tanks 100 spaced apart from each other at a predetermined distance and provided side by side; and a plurality of tubes 200 each having two opposite ends fixed to the header tanks 100 and arranged in two rows in a forward/rearward direction while defining flow paths for heat exchange media. Further, the heat exchanger 1000 may further include a plurality of fins interposed between the tubes 200.

In this case, in the heat exchanger 1000, an internal space of the header tank 100 is partitioned and isolated by a partition wall 125 in the forward/rearward direction, such that the heat exchange media having different average temperatures flow in front and rear heat exchange parts, respectively. That is, the heat exchanger is similar in shape to a general two-row heat exchanger. Because the partition wall 125 completely isolate the front heat exchange part and the rear heat exchange part, the different heat exchange media may independently flow in the front heat exchange part and the rear heat exchange part. For example, a radiator or the like in which a high-temperature coolant and a low-temperature coolant flow may be used as the heat exchanger configured such that different types of heat exchange media having average temperatures different for respective regions flow. In this case, the high-temperature coolant may serve to remove heat from an engine while flowing through a coolant circuit including the engine. The low-temperature coolant may serve to cool electrical components having a relatively low temperature while flowing through a coolant circuit including the electrical components.

In the heat exchanger described above, a degree of thermal expansion is, of course, different between a portion where a high-temperature heat exchange medium flows and a portion where a low-temperature heat exchange medium flows. There is no great problem when degrees of thermal expansion are uniform in all the components of the heat exchanger in the state in which the components of the heat exchanger are securely fixed to one another by welding. However, in case that the portions greatly different in degrees of thermal expansion are locally formed, thermal stress is naturally and excessively concentrated at the corresponding portions, which causes damage. In the case of the heat exchanger 1000 of the present invention, a portion in the vicinity of the partition wall 125, which is a boundary line between the front and rear heat exchange parts, is a portion where thermal stress is most concentrated.

The present invention is intended to reduce thermal stress concentration at this portion. Because temperature range conditions of the heat exchange media, which respectively flow in the front and rear heat exchange parts, cannot be changed, it is impossible to remove a phenomenon in which thermal stress is concentrated. However, it can be expected that the thermal stress concentration may be further reduced in case that a degree to which the temperature range is rapidly changed before and after the boundary line is further mitigated, i.e., in case that the temperature range is more gently changed in the vicinity of the boundary line.

That is, in the present invention, the partition wall 125 has a thermal stress reducing means, thereby solving the above-mentioned problem. In this case, as one embodiment, the thermal stress reducing means may be a flow distribution structure. As another embodiment, the thermal stress reducing means may be an air pocket. Hereinafter, the flow distribution structure and the air pocket will be described in more detail.

[1] One Embodiment of Thermal Stress Reducing Means: Flow Distribution Structure

As one embodiment of the thermal stress reducing means, in the present invention, the flow distribution structure is formed on the tank 120 in a partition wall vicinity region adjacent to the partition wall 125 that is the boundary line between the front and rear heat exchange parts, thereby reducing flow rates of the heat exchange media. More specifically, a flow rate of the heat exchange medium flowing in an internal space of the tube 200 in the partition wall vicinity region is relatively lower than a flow rate of the heat exchange medium flowing in the internal space of the tube 200 in the remaining region. With the above-mentioned configuration, the amount of heat exchange medium present in the partition wall vicinity region may be reduced, such that a temperature gradient is more gently changed, and as a result, thermal stress concentration may be further mitigated. That is, the flow distribution structure serves as the thermal stress reducing means.

FIG. 2 is a perspective view of a first embodiment of an integrated heat exchanger tank structure of the present invention, and FIG. 3 is a cross-sectional view of the first embodiment of the integrated heat exchanger tank structure of the present invention. (For reference, to implement sealability, a general gasket is further provided at a portion where the header 110 and the tank 120 are coupled. However, for simplification of the drawings, a gasket is omitted from the perspective view in FIG. 2 , and a gasket 150 is illustrated in FIG. 3 .) In the first embodiment, the flow distribution structure is configured as a flow rate adjustment baffle 121 having one end fixed to an inner surface of the tank 120, and the other end spaced apart from the internal space of the tube 200, the flow rate adjustment baffle 121 being configured to reduce the flow rate of the heat exchange medium flowing in the internal space of the tube 200 in the partition wall vicinity region. As illustrated in FIG. 3 , the other end of the flow rate adjustment baffle 121 is illustrated as being spaced apart upward from an end of the tube 200 at a predetermined distance and covering an opening portion of a part of the end of the tube 200, but the present invention is not limited thereto. For example, the other end of the flow rate adjustment baffle 121 may extend to the internal space of the tube 200. In this case, an outer diameter of the other end of the flow rate adjustment baffle 121 may be slightly smaller than an inner diameter of the tube 200. That is, in this case, the other end of the flow rate adjustment baffle 121 is fitted into the internal space of the tube 200 while defining a small gap. Therefore, it is possible to reduce the flow rate by reducing an area of a flow path. Meanwhile, the flow rate adjustment baffle 121 is a structure fixed to the tank 120 and may be integrated with the tank 120 by being manufactured by using a single mold. As illustrated in FIG. 3 , one end of the flow rate adjustment baffle 121 may extend and be connected to a ceiling of the inner surface of the tank 120 in consideration of manufacturing convenience.

FIG. 4 is a perspective view of a second embodiment of the integrated heat exchanger tank structure of the present invention, and FIG. 5 is a cross-sectional view of the second embodiment of the integrated heat exchanger tank structure of the present invention. (Even in this case, like FIGS. 2 and 3 , the gasket is omitted from FIG. 4 , and the gasket 150 is illustrated in FIG. 5 .) In the second embodiment, the flow distribution structure is configured as a flow rate adjustment rib 122 formed as a part of the tank 120 protrudes toward the inside of the header tank 100, and an end of the protruding portion is disposed to be spaced apart from the internal space of the tube 200. The flow rate adjustment rib 122 is formed to reduce the flow rate of the heat exchange medium flowing in the internal space of the tube 200 in the partition wall vicinity region. Unlike the first embodiment in which the flow rate adjustment baffle 121 is configured as a separate member and assembled to the tank 120, the flow rate adjustment rib 122 may be integrated with the tank 120, as illustrated. Like the flow rate adjustment baffle 121, the flow rate adjustment rib 122 is also formed to cover the opening portion of a part of the end of the tube 200, thereby reducing the flow rate of the heat exchange medium flowing into the internal space of the tube 200.

The flow distribution structure may be formed on one of the front and rear heat exchange parts where a temperature of the heat exchange medium is relatively high. This is because a degree of thermal expansion increases as a temperature of the heat exchange medium increases, and the amount of thermal stress concentration increases. The drawings illustrate that a temperature of the heat exchange medium flowing in the rear heat exchange part is higher than a temperature of the heat exchange medium flowing in the front heat exchange part, and the flow distribution structure is formed in the rear heat exchange part. The assumption is made that a direction in which outside air is blown inward is defined as a forward direction and a direction in which outside air is blown outward is defined as a rearward direction. In case that the heat exchange medium having a higher temperature flows in the front heat exchange part, the air having passed through the front heat exchange part has already absorbed an excessively large amount of heat. For this reason, the air cannot sufficiently absorb heat in the rear heat exchange part, which may cause concern that heat exchange performance deteriorates in the rear heat exchange part. In consideration of the above-mentioned situation, the heat exchange medium having a higher temperature generally flows in the rear heat exchange part in the heat exchanger in which the heat exchange parts are disposed in parallel in the forward/rearward direction. That is, from a general design trend, the flow distribution structure may be formed in the rear heat exchange part.

Meanwhile, in the present invention, because the thermal stress concentration occurs over the entire front and rear heat exchange parts, the flow distribution structure may be applied to all the positions of the tube 200. In addition, the flow distribution structure may be formed to be spaced apart from only the position opposite to the position of the tube 200 in order to prevent the flow distribution structure from excessively occupying the internal space of the header tank 100.

In addition, the flow distribution structure may be formed so that degrees to which the flow of the heat exchange media is reduced at the positions of the tubes 200 are equal to one another. That is, degrees to which the ends of the tubes 200 are covered are equal to one another in respect to all the tubes 200. However, the present invention is not necessarily limited thereto. This configuration will be described in detail. In the heat exchange part, a temperature is lowered during a process in which the high-temperature heat exchange medium is introduced into an inlet port and exchange heat with outside air while flowing through the heat exchange part. The heat exchange medium having a temperature, which has become a low temperature as described above, is discharged to a discharge port. That is, even in the single heat exchange part, a temperature of the heat exchange medium at the inlet port is relatively high, and a temperature of the heat exchange medium at the discharge port is relatively low. In this case, the assumption is made that the high-temperature heat exchange part, in which the high-temperature heat exchange medium having a high average temperature flows, and the low-temperature heat exchange part, in which the low-temperature heat exchange medium having a low average temperature flows, are disposed in parallel. According to the above-mentioned principle, in each of the high-temperature heat exchange part and the low-temperature heat exchange part, a temperature at the inlet port is highest, and a temperature at the discharge port is lowest. In this case, in case that a side of the discharge port of the high-temperature heat exchange part (a portion where a temperature is lowest in the high-temperature heat exchange part) and a side of the inlet port of the low-temperature heat exchange part (a portion where a temperature is highest in the low-temperature heat exchange part) are disposed adjacent to each other, a temperature difference between the high-temperature heat exchange part and the low-temperature heat exchange part does not greatly occur in the above-mentioned sides. Meanwhile, with the above-mentioned configuration, at the opposite side, a side of the inlet port of the high-temperature heat exchange part (a portion where a temperature is highest in the high-temperature heat exchange part) and a side of the discharge port of the low-temperature heat exchange part (a portion where a temperature is lowest in the low-temperature heat exchange part) are disposed adjacent to each other. In this case, a greatest temperature difference may occur. In this case, the design may be performed so that it is possible to further reduce the flow rate of the heat exchange medium by increasing a degree to which the tube is covered at the portion where a temperature difference is large, and it is possible to less reduce the flow rate of the heat exchange medium by decreasing a degree to which the tube is covered at the portion where a temperature difference is small. That is, as described above, the flow distribution structure may be formed so that the degrees to which the flow of the heat exchange media is reduced at the positions of the tubes 200 are different from one another.

FIG. 6 illustrates examples of temperature gradients in the related art and the present invention. Like the context previously described with reference to the arrangement of the heat exchange parts according to the temperatures in the general two-row heat exchanger, in the embodiment in FIG. 6 , a temperature of the heat exchange medium flowing in the rear heat exchange part is higher than a temperature of the heat exchange medium flowing in the front heat exchange part. That is, a temperature of a rear tube is higher than a temperature of a front tube. As illustrated in the view of <RELATED ART> at the left side, there is a significantly great temperature difference between the front and rear sides in the partition wall vicinity region. Meanwhile, as illustrated in the view of <PRESENT INVENTION> at the right side, it can be seen that a temperature difference spectrum between the front and rear sides in the partition wall vicinity region is widely distributed, i.e., a temperature is more gently changed in comparison with <RELATED ART>.

FIG. 7 is a graph for comparing temperature gradients between the related art and the present invention, i.e., a graph illustrating the result of FIG. 6 . The graph of <RELATED ART> is indicated by the dotted line, and the graph of <PRESENT INVENTION> is indicated by the solid line. As properly illustrated in FIG. 7 , in the case of <RELATED ART> in which no flow distribution structure is provided, there is a portion where a temperature gradient is rapidly curved. In contrast, in the case of <PRESENT INVENTION> in which the flow distribution structure is provided, it can be seen that the portion, which is rapidly curved in <RELATED ART>, has a significant gradual shape. Because the temperature gradient is gently formed as described above, the degree of thermal expansion may also be gently changed. As a result, the thermal stress concentration may be further mitigated and reduced in comparison with the related art.

Meanwhile, the flow distribution structure consequently reduces the flow rate of the heat exchange medium by covering a part of the tube and prevent the heat exchange medium from flowing into the tube well. In case that the flow distribution structure is excessively large, the flow distribution structure adversely affects the overall flow of the heat exchange medium, which may degrade heat exchange performance. In consideration of this situation, it is not preferred that the flow distribution structure is excessively large. In contrast, in case that the flow distribution structure is excessively small, the above-mentioned effect of mitigating the thermal stress concentration cannot be obtained. In consideration of the above-mentioned situations together with the aspect illustrated in the graph in FIG. 7 , the flow distribution structure may be formed to corresponding to a range of 10 to 20% of a width of the tube 200.

[2] Another Embodiment of Thermal Stress Reducing Means: Air Pocket

In the present invention described above, the flow distribution structure of the present invention is adopted when the heat exchange media having different temperatures flow in the two spaces of the header tank divided by the partition wall, which makes it possible to solve the problem in that a temperature gradient is rapidly changed at the periphery of the partition wall, and thermal stress concentration is caused by a rapid change in degree of thermal expansion. In the related art, it is impossible to excessively increase a temperature difference between the heat exchange media flowing in the two spaces of the header tank because of the problem of thermal stress concentration. However, it is possible to design and further increase a temperature difference between the heat exchange media by adopting the present invention in comparison with the related art.

However, in this case, the temperature difference between the parts is excessively great with the partition wall interposed therebetween, which may cause concern that significant unnecessary and undesired heat transfer occurs between the heat exchange media through the partition wall. Further, when the temperature difference between the two opposite sides of the partition wall is excessively large, the degrees of thermal expansion at the two opposite sides of the partition wall may be significantly unbalanced. Meanwhile, in general, in the heat exchanger header tank, a baffle extending in a direction of a cross-section of the header tank is often provided in addition to the partition wall extending in the longitudinal direction of the header tank in order to adjust a flow path for the heat exchange medium. However, when the degrees of thermal expansion at the two opposite sides of the partition wall are different in the two-row header tank, there is concern that the baffle formed to be suitable for an inner shape of the header tank is deformed, or the baffle and the tank are separated. FIG. 8 is a view illustrating an example of deformation of the baffle caused when a temperature difference between the heat exchange media at the two opposite sides of the integrated heat exchanger is large. When a gap is formed between the baffle 130 and the tank 120, the heat exchange medium flows into an undesired space, which may cause a problem in that designed heat exchange performance cannot be obtained.

A third embodiment is provided to prevent this problem, i.e., the problem in that in case that the temperature difference between the two opposite sides of the partition wall 125 is too large, the baffle 130 is deformed and distorted by a difference in degrees of thermal expansion between two opposite surfaces. FIG. 9 is a cross-sectional view of the third embodiment of the integrated heat exchanger tank structure of the present invention. As illustrated, in the third embodiment, an air pocket 123 is formed in the form of an empty space in the partition wall 125 or on the partition wall 125. As illustrated, the air pocket 123 may extend in an extension direction of the partition wall 125. The interior of the air pocket 123 is an empty space filled with air, which may effectively prevent unnecessary heat transfer through the partition wall 125. That is, in the present embodiment, the air pocket 123 is the thermal stress reducing means.

In addition, the air pocket 123 may be applied to the heat exchanger having the flow distribution structure described above. However, only the air pocket 123 may be applied without the flow distribution structure. Even in this case, a thermal insulation effect may further mitigate thermal stress concentration in the vicinity of the boundary line between the front and rear sides. That is, the heat exchanger 1000 of the present invention may appropriately selectively adopt one of or both the flow distribution structure described in [1] and the air pocket described in [2] as the thermal stress reducing means.

Meanwhile, the air pocket 123 may be provided only in the form of an empty space in the partition wall 125. There is no problem in forming the shape of the air pocket 123 in case that the tank 120 is manufactured by extrusion. However, in consideration of the concern that a defect rate increases when shape complexity increases, the air pocket 123 may be opened at an end directed toward the header 120, as illustrated in FIG. 9 . Because the partition wall 125 and the end of the air pocket 123 directed toward the header 120 are anyway sealed completely by the gasket 150, the configuration in which the end of the air pocket 123 directed toward the header 120 is opened does not affect the function of the partition wall 125 (the function of isolating the flow space of the heat exchange medium in the forward/rearward direction). That is, the opened portion of the air pocket 123 is sealed by the gasket 150. In this case, the gasket 150 may have a sealing protrusion 151 protruding at a position corresponding to the opened portion of the air pocket 123 in order to more securely ensure sealability of the opened portion of the air pocket 123. The sealing protrusion 151 may be inserted into the opened portion of the air pocket 123, such that the air pocket 123 may be securely sealed. Further, because the opened portion of the air pocket 123 naturally guides the sealing protrusion 151 during the insertion process, the sealing protrusion 151 also serves to prevent a situation in which the gasket 150 deviates from an exact position and is erroneously assembled at the time of assembling the gasket 150.

Meanwhile, the first embodiment of the flow distribution structure illustrated in FIGS. 2 and 3 is illustrated in FIG. 9 , but the present invention is not limited thereto. The air pocket 123 of the third embodiment may be applied to the second embodiment. Alternatively, the air pocket 123 may, of course, be applied to a heat exchanger to which the first and second embodiments are not applied.

FIG. 10 is a cross-sectional view of a fourth embodiment of the integrated heat exchanger tank structure of the present invention. In case that the air pocket 123 is formed in the partition wall 125 as described above, a leak check path 124 may be formed in the tank 120 and provided in the form of a flow path that allows the air pocket 123 to communicate with the outside. During a process of manufacturing the header tank 100, a leak test is necessarily performed by blowing air and checking whether there occurs a portion having a gap during the assembling process, i.e., whether there is concern that a leak occurs later when the heat exchange medium flows. In general, the leak test has been performed on the front and rear spaces. That is, the leak test has been necessarily performed twice in the related art. However, in case that the leak check path 124 is formed as described above, air is necessarily discharged to the leak check path 124 along the air pocket 123 when a gap is present between the partition wall 125 and the header 120. Therefore, the leak test may be simultaneously performed on the front and rear spaces. That is, because the leak check path 124 is formed, the number of leak test processes may be decreased from two to one, which makes it possible to improve productivity.

The present invention is not limited to the above embodiments, and the scope of application is diverse. Of course, various modifications and implementations made by any person skilled in the art to which the present invention pertains without departing from the subject matter of the present invention claimed in the claims.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1000: Heat exchanger     -   100: Header tank     -   110: Header     -   120: Tank     -   121: Flow distribution baffle     -   122: Flow distribution rib     -   123: Air pocket     -   124: Leak check path     -   125: Partition wall     -   150: Gasket     -   155: Sealing protrusion     -   200: Tube 

What is claimed is:
 1. A heat exchanger comprising: a pair of header tanks each having therein a fluid flow space defined by coupling a header and a tank, the pair of header tanks being spaced apart from each other at a predetermined distance and provided side by side; and a plurality of tubes each having two opposite ends fixed to the header tank and configured to define flow paths for heat exchange media, the plurality of tubes being arranged in two rows in a forward/rearward direction, wherein an internal space of the header tank is isolated and divided by a partition wall into front and rear heat exchange parts, wherein the heat exchange media having different average temperatures flow in the front and rear heat exchange parts, respectively, and wherein the partition wall has a thermal stress reducing means.
 2. The heat exchanger of claim 1, wherein the thermal stress reducing means is a flow distribution structure formed on the tank in a partition wall vicinity region adjacent to the partition wall that is a boundary line between the front and rear heat exchange parts, and the flow distribution structure is formed so that a flow rate of the heat exchange medium flowing in the internal space of the tube in the partition wall vicinity region is relatively lower than a flow rate of the heat exchange medium flowing in the internal space of the tube in the remaining region.
 3. The heat exchanger of claim 2, wherein the flow distribution structure is a flow rate adjustment baffle having one end fixed to an inner surface of the tank, and the other end disposed to be spaced apart from the internal space of the tube, the flow rate adjustment baffle being formed to reduce a flow rate of the heat exchange medium flowing in the internal space of the tube in the partition wall vicinity region.
 4. The heat exchanger of claim 2, wherein the flow distribution structure is a flow rate adjustment rib formed as a part of the tank protrudes to an inside of the header tank and an end of a protruding portion is disposed to be spaced apart from the internal space of the tube, and wherein the flow rate adjustment rib is formed to reduce a flow rate of the heat exchange medium flowing in the internal space of the tube in the partition wall vicinity region.
 5. The heat exchanger of claim 2, wherein the flow distribution structure is formed in one of the front and rear heat exchange parts where a temperature of the heat exchange medium is relatively high.
 6. The heat exchanger of claim 5, wherein a temperature of the heat exchange medium flowing in the rear heat exchange part is higher than a temperature of the heat exchange medium flowing in the front heat exchange part, and the heat exchanger the flow distribution structure is formed in the rear heat exchange part.
 7. The heat exchanger of claim 2, wherein the flow distribution structure is applied to all positions of the tubes.
 8. The heat exchanger of claim 2, wherein the flow distribution structure is formed to be spaced apart from only a position opposite to a position of the tube.
 9. The heat exchanger of claim 2, wherein the flow distribution structure is formed to correspond to a range of 10 to 20% of a width of the tube.
 10. The heat exchanger of claim 1, wherein the thermal stress reducing means is an air pocket formed in the form of an empty space in the partition wall.
 11. The heat exchanger of claim 10, wherein the air pocket extends in an extension direction of the partition wall.
 12. The heat exchanger of claim 10, wherein the air pocket is formed to be opened at an end directed toward the header.
 13. The heat exchanger of claim 12, wherein an opened portion of the air pocket is sealed by a gasket provided at a portion where the header and the tank are coupled.
 14. The heat exchanger of claim 13, wherein the gasket has a sealing protrusion protruding at a position corresponding to the opened portion of the air pocket.
 15. The heat exchanger of claim 10, wherein the heat exchanger has a leak check path formed in the tank and provided in the form of a flow path that allows the air pocket to communicate with the outside.
 16. The heat exchanger of claim 1, wherein the heat exchanger is a radiator in which a high-temperature coolant and a low-temperature coolant flow. 